Wedding Cake Help For A Newbie!

Hi all,I love decorating cakes but i'm not that good at cake making (i normally buy some and then cover them!!!). I've told a friend i'll happily decorate her wedding cake but its only just dawned on me that i've no idea about the best way to make the cake!

She wants three tiers, round, and ALL layers sponge!

Do i have a problem with the bottlom cake taking the weight?

How do i get each layer the same depth?

Can anyone recommend a good recipe for all three layers? (I'm from the uk so not good at translating cup measurements!!)

If anyone could help or direct me to where i need to find this info that would be fab!!

I'm sure i'll have loads of questions but there the one's that seem to play on my mind!!

Preheat the oven to 350 degrees Fahrenheit. Butter and line two 8 x 3-inch baking pans or one 12 x 3-inch pan with parchment.Sift together the flour and baking powder. Set aside.Cream the margarine in a large bowl with an electric mixer until fluffy and light in color, about 2 minutes on medium speed. Add the sugar and continue to mix until fluffy and light.Add the egg yolks, one at a time, being sure each is well incorporated before adding the next one. Add the vanilla.Reduce the mixer speed to low and add the dry ingredients alternately with the sour cream, beginning and ending with the flour. Be sure the mixture is completely blended after each addition. Scrape the sides of the bowl, and beat for 1 minute.In a separate bowl, with clean beaters, beat the egg whites to soft peaks. Gently fold the whipped egg whites into the batter with a rubber spatula.Pour the batter into the prepared pans and smooth with a rubber spatula. Bake in the preheated oven, 60 minutes for the 12-inch square pan or 45 to 50 minutes for the 8-inch pan. The top of the cake should be nicely browned. Test for doneness with a skewer or a toothpick; the tester should come out dry and clean.

Use baking strips or a wet towel cut into strips and wrapped around the tin (held in place with a safety pin) to make the cake bake level and evenly.

You use dowels to make sure the bottom cake takes the weight of the top 2 cakes.